Abstract Mathematical models are described in which the circulatory system of an organism is considered as a multifractal object. The solution to two problems is given. The first one is associated with the normal state of the body’s life support system, namely, to heat transfer in human skin. The equations of hydrodynamics and heat transfer are the basis of the model. Quantitative results of calculating

Abstract Elevated expression of the col2a1 gene responsible for synthesis of type II collagen, a major extracellular matrix protein of hyaline cartilage, was observed in multipotent stem cells of rat bone marrow exposed to low-power laser radiation with a wavelength of 0.63 μm and power of 1.7 mW. The result suggests that this procedure may be employed in treatment of diseases associated with damage

Abstract A spectrometer based on silicon nanosandwiches (SNSs) is proposed for problems of personalized medicine. SNS structures exhibit properties of terahertz (THz) emitter and receiver of the THz response of biological tissue. Measurements of the I–V characteristics of the SNS structure make it possible to analyze the spectral composition of the THz response of biological tissue and determine relative

Abstract We consider the effect of various radio frequency (rf) pulse sequences on the contrast of magnetic resonance (MR) images. We have developed a program for simulating magnetic resonance tomograms and for determining optimal values of parameters of rf pulse sequences for obtaining the best contrast of MR images. This program has been tested for MRI experiments with negative contrast agents based

Abstract The results of an investigation intended to develop a mathematical model representation of the left ventricular myocardium in the polar bull’s eye map mode are presented. Comparison of images obtained using the numerical simulation and the cases in clinical practice allows evaluating possible errors and discrepancies of reconstruction in the single-photon emission computed tomography.

Abstract A novel technological approach based on ion implantation for obtaining nanostructured substrates for the visual characterization of ultrasmall biological objects and microorganisms has been described. By means of argon-ion implantation of silicate glasses through surface masks made of copper wire mesh, periodic microstructures in the form of gratings with mesh sizes of 50 × 50 μm were formed

Abstract To characterize the effect of oxidative stress (OS) on the ability of erythrocytes to pass through microvessels and capillaries, we studied the dynamics of the movement of human erythrocytes in vitro, in the channels of a microfluidic device, under the action of an OS inducer, tert-butyl hydroperoxide (tBH), and compared it with a cytological assessment of the transformation of cell membranes

Abstract The method of scanning electron microscopy in complex with energy dispersive spectrometric analysis is applied for the first time for studying the composition of materials used or medical purposes. Cartilage implants have been formed based on polyacrylamide hydrogels reinforced by bacterial and plant celluloses, and the dynamics of variation of compositions of implant and the boundary osteal

Abstract The results of a numerical study of heating and destruction of a biological tissue under the action of a series of focused ultrasound pulses generated by a multielement array (tumor treatment programs) are presented. Irradiation programs are considered that differ in the locations of focal points within a tissue (the Archimedean and “square” spirals), the number of pulses in the series, and

Abstract A number of models of the polymerase chain reaction have been suggested to date with the aim of gaining exact quantitative estimates for reaction products. These models usually identify the reaction product kinetics with a kinetics of fluorescence reporter. Here, a model of polymerase chain reaction is suggested in which the results of the reaction are detected using an intercalating dye.

Abstract A model of a Frenkel gas–solid system that consists of H2O molecules and H3O+ and OH– ions and has the same density and particle concentration as liquid water has been considered. Particles execute thermal vibrational–diffusion motion, in the course of which they collide, exchange protons, and interconvert. Under the assumption that the medium persists owing to ion–dipole forces, it has been

Abstract Using the method for distinguishing the principal components associated with the correlation coefficients of the Pearson matrix, a possible relationship has been found between the incidence of type 1 diabetes mellitus and various urbanization factors in the Russian Federation. A hypothetical physical model of the impact of urbanization factors on the incidence of the disease has been created

Abstract Experimental data on the production of dry powders of immobilized biological preparations intended for treatment of oil-contaminated soil were obtained. The carbonization of biopolymers (starch, lignin) using self-propagating high-temperature synthesis was used as the basic method for obtaining 2D carbon structures used as a matrix for immobilization of oil-destructor microorganisms. Oil-destructor

Abstract A problem of fabrication of magnetic polymer capsules for targeted drug delivery is considered. Magnetic nanoparticles are used in the problem under study. A method for fabrication of such particles involving synthesis of layered nanowires with alternating layers of the specified magnetic metal and sacrificial layers of nonmagnetic metal is proposed. A method for template-assisted synthesis

Abstract Dentin in the human tooth is a natural composite material with a complex multilevel hierarchical structure and consists of micro and nanostructures that are related to each other in a complex interrelation governed by laws that have not been fully understood yet. To identify the relationship between the dentin structure and its mechanical properties, we study samples prepared from human molars

Abstract Numerical experiments based on the Peyrard–Bishop–Holstein model have been conducted to demonstrate the possibility of charge transfer by polarons in the homogeneous Poly G/Poly C-chain of DNA subjected to a constant electric field. It has been shown that a polaron in this model can travel large distances along the chain with a constant velocity if the electric field is weak. The charge motion

Abstract The temperature dependences of the veloсity of hypersound (V(T)) in solutions with various concentrations of guanidine hydrochloride (GndHCl) are studied by Brillouin–Mandelstam light scattering spectroscopy in the temperature range from 263 to 353 K. It is shown that the temperature dependence of the sound velocity has a pronounced maximum at low concentrations of GndHCl. An increase in the

Abstract We present the results of studies of the interaction of cells with various materials and products from them intended for biomedical use. Widefield fluorescence microscopy enables evaluating the cytotoxicity of samples, cell viability, morphology, and proliferative activity in the process of interaction with the test samples, as well as adhesion, migration, and cell distribution both on the

Abstract Synthetic hydroxyapatite nanoparticles that contain ammonium chloride crystals are obtained. The X-ray diffraction, thermogravimetric analysis, and BET methods show that ammonium chloride crystals are decomposed in argon in the temperature range of T = 220–270°C. The heat treatment at T = 300°C gives thermal stability to the nanoparticles. The presence of ammonium chloride in the culture medium

Abstract The structure and morphology of aqueous dispersions, the gelation, and the intermolecular interactions of water molecules with a Synthanol ALM-10 non-ionic low-molecular surfactant have been investigated using viscosimetry, thermogravimetric analysis, IR spectroscopy, and phase-contrast and polarization optical microscopy in the entire range of concentrations (from 0 to 100 wt %). The polymorphism

AbstractSupersonic jets are widely used in devices based on a self-oscillation process emerging during the interaction of a gas flow with tubular cavities (gas-jet acoustic emitters). We analyze the mechanisms for sustaining undamped pulsations of pressure and determine the flow field in a tubular cavity during the interaction of an underexpanded supersonic jet with it. We consider the physical pattern

AbstractThe phenomenological mechanisms for increasing the unipolarity under thermal processing in the short-circuiting conditions for heavily doped LiNbO3:ZnO crystals are analyzed by comparing with the temperature behavior of nominally pure LiNbO3:ZnO crystals with the congruent composition. It is shown that an increase in the unipolarity and, hence, the disappearance of the domain structure in heavily

AbstractA new silver-based electrocontact material dispersion-strengthened with nanopowders of zinc, tin, and titanium oxides has been obtained. The microstructure and elemental composition of the phases formed during solid-phase sintering and electroerosive tests have been studied by electron microscopy and energy-dispersive microanalysis. The electroerosive wear is determined during laboratory tests

AbstractLaunching and control of pyrotechnical systems at a specified coordinate is among the most complicated problems in the tests at a missile track. A method for launching and a corresponding device are proposed for activation of pyrothechnical systems of missile trains boosting along an ejection path to hypersonic velocities with ejection of an object to free flight. The method is based on generation

AbstractWe consider the realization of rotation of particles with a photoinduced dipole moment in the absence of an external field source. The effects considered here are based on the mechanism of the orientational interaction of at least a pair of particles that are photodipoles. We consider examples of realization of this mechanism including the geometry corresponding to the Quincke photorotation

AbstractWe report on the results of experimental investigation of forced action of a deeply subcritical microwave discharge initiated in a quasi-optical electromagnetic beam on bodies placed into a supersonic air flow.

AbstractWe have studied the spectral and dynamic characteristics of quantum cascade lasers emitting in the long-wavelength infrared range. It is shown that lasers with a short cavity (~1 mm) make it possible to obtain frequency combs in a very wide spectral range. We have investigated the spectral dynamics in the frequency comb generation regime. It is demonstrated that the intensity of longitudinal

AbstractThe results of experiments on the influence of a weak magnetic field on the sensitivity of powdered pentaammine (5-nytrotetrazolato-N2) cobalt(III) perchlorate to a high-current electron beam of nanosecond duration have been presented. In the experiments, two types of pentaammine (5-nytrotetrazolato-N2) cobalt(III) perchlorate powder were used: medium- and fine-dispersed ones. It has been found

AbstractThe interaction between microwave electromagnetic waves and conducting films with a nanometer thickness in the homogeneous region approximation and a structure consisting of micro- and nanoparticles has been numerically simulated. Using rigorous coupled-wave analysis, the dynamics of the changes in the optical coefficients from the values characteristic of a dielectric to the values for a homogeneous

AbstractThe effect of bulk radiative heat transfer during the growth of profiled sapphire crystals from the melt is studied by the numerical simulation method. The peculiarities in the structure of a lightguide flow in the crystal and in the melt, as well as the possibility of radiation instability of the interface, are considered. It is shown that overcooled regions with the size determined by the

AbstractWe have designed a silicon avalanche photodiode for detecting vacuum ultraviolet radiation. The external quantum yield of a silicon avalanche photodiode has been investigated in the wavelength range of 120–170 nm. It is shown that the avalanche photodiode has an external quantum yield of 24–150 electrons/photons at a reverse bias voltage of 230–345 V. Testing of this avalanche photodiode with

AbstractThe structure of electrohydrodynamic (EHD) flows in a variable electric field has been investigated based on computer simulation of EHD flows in a needle–plane electrode system. The characteristic frequency interval of a feed sine-wave voltage with an amplitude of 5 kV has been considered. Changes in the charge and velocity structures of EHD flows are described, and the characteristic features

AbstractAn experimental study of the self electromagnetic field generated by the low-temperature plasma of the fuel combustion products of a model liquid-propellant rocket engine is carried out. The fuel components were gaseous oxygen and ethyl alcohol. When modeling emergency situations in the operation of the model rocket engine, the intensity of its self electromagnetic field generated by the ionized

AbstractA continuum mathematical model of low-concentration suspension transfer without mixing in a plane vertical gravitational classifier under conditions of phase flux balance is suggested. The flow of a carrier medium is assumed to be laminar, and no limitations on the particle sedimentation rate are imposed. Analytical relationships to calculate the local counting functions of the particle size

AbstractWe communicate the results of calculations and selection methods, and identify the properties, of inhibitors that block the formation of high-molecular-weight structures from amyloid peptides, with their blocking mechanism explained. We consider in detail the biochemical requirements for, and the criteria and conditions for identification of, inhibitors that prevent amyloids from forming higher-order

AbstractThe surfaces of Yb–Si(111) and O–Yb–Si(111) structures (with a thickness of ytterbium nanofilms of 16 monolayers (6.08 nm)) have been investigated for the first time using scanning tunnel microscopy, which has provided data on the morphology and phase composition of these surfaces. It is found that, prior to oxygen adsorption, the nanofilms exhibit a high degree of homogeneity over their thickness

AbstractIt has been shown that microwave radiation induces structural and, as a consequence, magnetic phase transformations in iron oxide α-Fe2O3 (hematite). After microwave irradiation of fine-dispersed partially amorphized Fe2O3 particles for 10 min in wet air, the percentage of crystalline hematite drops by 40% but the total amount of crystalline components increases owing to the formation of a

AbstractA need to study the structure of the NMR signals detected with the aid of the modulation method is substantiated. Specific features of the detection of the NMR signals using the modulation method that depend on the properties of condensed (flowing or stationary) medium are determined. A new method is proposed to determine contributions of the absorption and dispersion signals to the detected

AbstractEvolution of bunching and harmonic power is theoretically studied for a single-pass free-electron laser (FEL) in which electrons are periodically phase-shifted relative to photons in intervals between undulators with harmonics of magnetic field. Analytical calculations are used to reveal the configuration of magnetic field of an asymmetric elliptical and planar undulators that make it possible

AbstractThe principal limitations imposed by spin (or atomic) quantum projection noise on the sensitivity of optical quantum sensors on thermal atoms, which include frequency standards, magnetometers, and gyroscopes that use optical detection of electron paramagnetic resonance, have been theoretically and experimentally studied. The effect of increasing the rms amplitude of the projection noise in

AbstractHeat transfer in a water drop containing eosine and ablation silver nanoparticles induced by stationary visible laser irradiation, λ = 532 nm, and pulsed IR laser irradiation, λ = 10.6 μm (VIS–IR double laser irradiation), has been studied in the temperature interval of 0.2–50°C. It has been found that the vibratory system of triplet states in a dye molecule heats up after VIS–IR laser irradiation

AbstractThe effect of magnetically dependent absorption of radio-frequency high-frequency radiation detected by the method of optically detected magnetic resonance has been studied, and an explanation for it is proposed. A method of high-frequency excitation of optically detected magnetic resonance in nitrogen-vacancy color centers in a diamond crystal has been experimentally studied that provides

AbstractCu–14 wt% Al–4 wt% Ni alloy demonstrating the shape memory effect has been subjected to plastic deformation by means of uniaxial compression (upset). The process has been controlled by measuring the strain rate, applied stress, and compression ratio of standard specimens under isothermal conditions in the interval 400–600°C. Structural modifications in the alloy after mechanical tests have

AbstractThe article presents experimental results of changes in the dielectric and mechanical characteristics of spheroplastics based on an organosilicon elastomer and metallized glass microspheres caused by static and shock compression. Two regions of the frequency dispersion of the dielectric constant are established that are associated with the metal coating of microspheres. It was found that both

AbstractA model that describes amorphous–nanocrystalline transformation induced by either thermal annealing or millisecond thermal pulse is proposed. Generation of nanocrystals in the film is a relay process in which a transformation wave moves from the heated surface. The proposed approach takes into account specific features of the pulsed thermal source: surface type, short-term effect, and high

AbstractA composite based on ultra-high-molecular-weight polyethylene (UHMWPE) added with 1 wt % of multiwalled carbon nanotubes (MWCNTs) with a high permittivity (ε = 4.5) and a low dielectric loss (tanδ = 10–2) in the frequency range from 100 Hz to 100 MHz has been synthesized, and its main mechanical characteristics have been studied. The material has a low (22 MPa) breaking strength, a high (700%)

AbstractThe composition, structure, and surface topology of as-cast, homogenized, and nitrogenized alloy based on an intermetallic compound Sm2Fe17 with partial substitution of samarium atoms with holmium atoms have been studied using X-ray fluorescence and X-ray phase analysis, as well as scanning electron microscopy. Results on the magnetic properties of the initial compound Sm1.2Ho0.8Fe17 and the

AbstractExpressions describing the time of flight of charged particles taking into account time-of-flight chromatic aberrations in electrostatic mirrors with rotational symmetry are presented. By numerical calculations, the conditions of time-of-flight focusing of particles by energy up to the third order inclusively in the three-electrode mirrors, the electrodes of which are coaxial cylinders of equal

AbstractThe formation of zinc stannate nanostructures, which are of interest for sensorics, solar power, and transparent conductive electronics, has been considered. The structures have been synthesized by the hydrothermal method, with zinc oxide nanorods used as references in the case of synthesis time variation, and studied by X-ray photoelectron spectroscopy. This method has been shown to be effective

Abstract“Physical detonation” is a phenomenon in which detonation is induced by not chemical, but physical, energy concentrated in internal degrees of freedom (in the present case, in vibrational degrees of freedom of hydrogen molecules). The possibility of emergence of such a phenomenon in hydrogen preliminarily excited to a certain temperature in a shock tube is investigated by the Monte Carlo method

AbstractWe have designed a device with a gliding unipolar arc of the Jacob’s ladder type. The dynamics of arc rising has been investigated. It is found that the arc climbs at a constant velocity on the major part of its path. The convective nature of the arc rise due to heating of air by the plasma is demonstrated. The dependence of the arc rise velocity on the opening angle between the electrodes

AbstractAnalytical formulas for the amplitude–frequency and phase–frequency characteristics, as well as forced oscillations, of a fractional oscillator have been derived using the harmonic balance method. It has been found that these characteristics depend on the dissipative properties of a medium—memory effects, which are described by fractional-order derivatives. It has been shown that fractional

AbstractThe results of an experimental study of the relationship between the width of the turbulent combustion zone (TCZ) and the composition of the composite fuel (hythane), the maximum pressure in the combustion chamber of variable volume, and the propagation speed and electrical conductivity of the turbulent flame are presented. It was found that the width of the TCZ has a characteristic dependence

AbstractAfter repeated exposure to an arc vacuum discharge, Cu (60%)—Cr (40%) alloyed systems show a change in the atomic concentration of copper (from 53.7 to 71.8 at %) and, correspondingly, of chromium. Mass spectrometry showed the presence in the residual atmosphere of diffusion devices of fragments of Cx\({\text{H}}_{y}^{ + }\)-type molecules and molecules desorbed from all parts of the chamber—residual

AbstractSamples of tricadmium diarsenide with MnAs nanogranules (44.7 mol % MnAs) are synthesized. The morphology of the samples is studied by X-ray phase analysis and electron microscopy. The electrical properties of tricadmium diarsenide with MnAs nanogranules are studied in a range of temperatures of 77–372 K. It is found that the voltammetric characteristics are symmetrical relative to the inversion

AbstractHeating and vaporization of quartz particles in argon-plasma flow of an RF inductively coupled plasma torch is numerically simulated using a model of two-phase collisionless monodispersed mixture. Conditions for flow regimes with the ring-type frontal vortex and complete or partial penetration of particles to the high-temperature region of discharge are determined. Dependences of the degree

AbstractWe report on the results of first practical observations of sputtering of the Si surface during the implantation with Ag+ ions with an energy of 30 keV depending on irradiation dose D in the interval from 2.5 × 1016 to 1.5 × 1017 ion/cm2 for a fixed value of ion beam current density J = 8 μA/cm2, as well as for variation of J = 2, 5, 8, 15, and 20 μA/cm2 at constant D = 1.5 × 1017 ion/cm2.

AbstractNeutron stress diffractometry is used to study internal (residual) stress in a tape made of the AISI 310S stainless steel with a thickness of 100 μm and a width of 4 mm in three directions (along, across, and perpendicularly to the rolling plane). The residual macrostresses averaged over the tape length are determined at a segment of 40 cm. The macrostress distribution indicates a crescent-type

AbstractNanocrystalline cobalt oxide Co3O4 and composite ZnO/Co3O4 are obtained by chemical deposition from solutions followed by thermal annealing. It is shown that the presence of zinc oxide particles during synthesis radically changes the mechanism of the cobalt carbonates growth, which leads to a change in the phase composition, morphology, and properties of the material. The resistivity of the

AbstractWe compared several generalizations of the Bruggeman effective medium approach with the use of elliptical cells. Namely, a “uniaxial” anisotropic approximation and two isotropic models with averaging over chaotic orientations and random conductivities of particles were compared, which make it possible to consider multicomponent composites with various filler particles (for instance, carbon